Hepatocellular Carcinoma (HCC)
Hepatocellular carcinoma (HCC) arises from the main cells of the liver (the hepatocytes) and accounts for around 80% of all cases of liver cancer. It is usually confined to the liver and is associated with cirrhosis in 50% to 80% of patients. Hepatocellular carcinoma is about 3 times more common in males than in females. Chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) is a major cause of HCC and is responsible for making liver cancer the most common cancer in many parts of the world. In the United States, hepatitis C infection is responsible for about 50% to 60% of all liver cancers and hepatitis B is responsible for another 20%. Exposure to Aflatoxins is also a cause of HCC, mostly in warmer and tropical countries.
Liver cancer accounts for about 5.8% of all cancer cases globally (about 626,000 cases) and 8.9% of deaths per year (about 598,000). It is the 3rd most common cause of cancer-related death in both men and women worldwide. HCC is predominantly found in Asia and Africa, which account for 80% of cases. In the USA, there are approximately 18,500 new cases of HCC and 16,000 deaths per year.
About 85% of people diagnosed with liver cancer are between 45 and 85 years of age. About 4% are between 35 and 44 years of age and only 2.4% are younger than 35.
Hepatocellular Carcinoma Diagnosis:
Since symptoms of liver cancer often do not appear until the disease is advanced, only a small number of liver cancers are found in the early stages and can be removed with surgery. Many signs and symptoms of liver cancer are relatively nonspecific—that is, they can be caused by other cancers or by non-cancerous diseases. Imaging tests such as ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and angiography are commonly used to diagnose HCC. Other diagnostic tools include laparoscopy, biopsy, alpha-fetoprotein (AFP) blood test, liver function tests (LFTs), a prothrombin time (PT) and tests for hepatitis B and C.
Hepatocellular Carcinoma Staging:
HCC has four stages, stage I to stage IV according to the American Joint Committee on Cancer (AJCC) TNM system. HCC can be classified as localized resectable, localized unresectable or advanced. The overall 5-year relative survival rate from liver cancer is about 9%. One reason for this low survival rate is that most patients with liver cancer also have cirrhosis of the liver, which itself can be fatal (people with liver cancer and class C cirrhosis are generally too sick for any treatment and usually die in a few months). The 5 year survival for localized resectable HCC following surgery is between 40% and 70%. For advanced HCC there is no standard treatment and the 5 year survival rate is less than 5%. Survival continues to drop after diagnosis and treatment so that by 10 years it is half of what it was at 5 years.
Hepatocellular Carcinoma Treatment:
Treatment of liver cancer depends on the size of the tumor and whether the patient has cirrhosis. At this time, surgery, either by resection or liver transplantation, offers the only chance to cure a liver cancer. People without cirrhosis can do well with surgical removal of the tumor. However, in many cases, it might not be possible to safely remove a localized liver cancer. Less than 30% of the patients having explorative surgery are able to have their cancer completely removed by surgery. Partial hepatectomy results in a 5-year survival of 30% to 40%. If there is cirrhosis, or a very large tumor, most experts recommend liver transplantation as the main treatment. The 5-year survival for liver transplantation patients is around 70% but the opportunities for liver transplantation are limited.
Other treatments include radiofrequency ablation (RFA), ethanol ablation, cryosurgery, hepatic artery embolization, chemoembolization or three-dimensional conformal radiation therapy (3DCRT). Chemotherapy can also be used but shrinks fewer than 1 in 5 tumors. This may be improved by hepatic artery infusion (HAI). Chemotherapeutic agents used include Adriamycin, VP-16, Cisplatinum, Mitomycin, 5-FU and Leucovorin.
The prognosis for any treated primary liver cancer patient with progressing, recurring, or relapsing disease is poor. Treatment of liver cancer that returns after initial therapy depends on many factors, including the site of the recurrence, the type of initial treatment, and the functioning of the liver. Patients with localized resectable disease that recurs in the same spot may be eligible for further surgery.
Glioblastoma
Glioblastoma, also known as glioblastoma multiforme, may develop from a diffuse astrocytoma or an anaplastic astrocytoma but more commonly presents de novo without evidence of a less malignant precursor. Histologically, this tumor is an anaplastic, cellular glioma composed of poorly differentiated, often pleomorphic astrocytic tumor cells with marked nuclear atypia and brisk mitotic activity. Glioblastoma primarily affects the cerebral hemispheres. CNS tumors are associated with characteristic patterns of altered oncogenes, altered tumor-suppressor genes, and chromosomal abnormalities.
Glioblastoma accounts for approximately 12% to 15% of all brain tumors (which account for 85% to 90% of all primary central nervous system (CNS) tumors). New cases for CNS tumors in USA are approximately 18,800 (6.6 per 100,000 persons) per year, with around 12,800 (4.7 per 100,000 persons) deaths. This type of cancer accounts for approximately 1.3% of all cancers and 2.2% of all cancer-related deaths in the USA. Worldwide, there are approximately 176,000 new cases of brain and other CNS tumors per year, with an estimated mortality of 128,000. In general, the incidence of primary brain tumors is higher in whites than in blacks, and mortality is higher in males than in females. The peak incidence occurs between the ages of 45 and 70 years.
Primary brain tumors rarely spread to other areas of the body, but they can spread to other parts of the brain and to the spinal axis. Most patients with central nervous system (CNS) neoplasms do not live long enough to develop metastatic disease.
Glioblastoma Diagnosis:
Computed tomography (CT) and magnetic resonance imaging (MRI) have complementary roles in the diagnosis of CNS neoplasms. Angiography can also be used in diagnosis. In post-therapy imaging, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) may be useful in differentiating tumor recurrence from radiation necrosis. A definite diagnosis is then made by performing a biopsy.
Glioblastoma Staging:
Glioblastomas are among the most aggressively malignant human neoplasms, with a mean total length of disease in patients with primary glioblastoma of less than 1 year. On the WHO classification of nervous system tumors from grade I to grade IV, glioblastoma is classified as grade IV. The 5-year survival rate for patients with glioblastoma aged over 45 is 2% or less.
Glioblastoma Treatment:
The cure rate for glioblastoma is very low with standard local treatment. The first step in most cases is surgical removal by craniotomy of as much of the tumor as is safe without destroying normal function. Glioblastomas are not cured by surgery because cells from the tumor get too far into the normal surrounding brain tissue. However, surgery reduces the pressure of the tumor against the rest of the brain and can prolong life even though all of the tumor can't be removed.
Radiation therapy (external beam radiation, interstitial radiotherapy, 3D conformal therapy, stereotactic radiosurgery or brachytherapy) can increase the cure rate or prolong disease-free survival. Radiation therapy may also be useful in the treatment of recurrences in patients initially treated with surgery alone. Therapy can involve surgically implanted carmustine-impregnated polymer combined with postoperative external-beam radiation therapy (EBRT).
Chemotherapy is usually given along with or following radiation therapy and may prolong survival. Chemotherapeutic agents used include temozolomide, BCNU (carmustine) and cisplatin. Growth factor inhibitors erlotinib (Tarceva) and gefitinib (Iressa) have been shown to shrink tumors in some patients.
Novel biologic therapies under clinical evaluation for patients with brain tumors include dendritic cell vaccination, tyrosine kinase receptor inhibitors, farnesyl transferase inhibitors, viral-based gene therapy, and oncolytic viruses.
Lung Cancer
Lung cancer is the most common form of cancer worldwide (accounting for about 12% of cancer cases) and the main cause of death from cancer (accounting for about 18% of deaths). Global incidence of lung cancer is over 1,300,000 per year, with the number of deaths over 1,100,000. In the USA, there are about 170,000 new cases per year (about 13% of all cancers), with about 160,000 deaths (about 28% of cancer deaths). Lung cancer is much more prevalent among men than women. Nearly 70% of people diagnosed with lung cancer are older than 65; fewer than 3% of all cases are found in people under the age of 45. Around 15% of all lung cancers are small cell type (SCLC), which tend to spread widely through the body, while the remaining 85% are non-small cell (NSCLC). It has been estimated that approximately US $9.6 billion is spent in the USA each year on treating lung cancer.
Lung Cancer Diagnosis
Lung cancer is a life-threatening disease because it often metastasises even before it can be detected on a chest x-ray. Usually symptoms of lung cancer do not appear until the disease is in an advanced stage. So far, there is no screening test that has been shown to improve a person's chance for a cure. Imaging tests such as a chest x-ray, CT scan, MRI scan or PET scan may be used to detect lung cancer. Tests to confirm the diagnosis are then performed and include sputum cytology, needle biopsy, bronchoscopy, endobronchial ultrasound and complete blood count (CBC).
Lung Cancer Staging
Nearly 60% of people diagnosed with lung cancer die within one year of diagnosis; 75% die within 2 years. The 5-year survival rate for people diagnosed with NSCLC is about 15%; for SCLC the 5-year survival rate is about 6%. NSCLC is staged using the American Joint Committee on Cancer (AJCC) TNM system—Stage 0-Stage IV. The 5-year survival rates by stage are as follows: stage I: 47%; stage II; 26%; stage III: 8% and stage IV: 2%. SCLC has a 2-stage system—limited stage and extensive stage. About two thirds of SCLC patients have extensive disease at diagnosis. If SCLC is found very early and is localised to the lung alone, the 5-year survival rate is around 21%, but only 6% of patients fall into this category. Where the cancer has spread, the 5-year survival is around 11%. For patients with extensive disease, the 5-year survival is just 2%.
Lung Cancer Treatment
Surgery is the only reliable method to cure NSCLC. Types of surgery include lobectomy, pneumonectomy, segmentectomy and video-assisted thoracic surgery (for small tumours). External beam radiation therapy is sometimes used as the primary treatment, especially if the patient's health is too poor to undergo surgery. Radiation therapy can also be used after surgery. Chemotherapy may be given as the primary treatment or as an adjuvant to surgery. Targeted therapy using epidermal growth factor receptor (EGFR) antagonists such as gefitinib or erlotinib can also be given after other treatments have failed. Antiangiogenic drugs, such as bevacizumab, have been found to prolong survival of patients with advanced lung cancer. Photodynamic therapy is also being researched as a treatment for lung cancer.
The main treatment for SCLC is chemotherapy, either alone or in combination with external beam radiation therapy and very rarely, surgery.
Chemotherapeutic agents used for NSCLC and SCLC include cisplatin, carboplatin, mitomycin C, ifosfamide, vinblastine, gemcitabine, etoposide, vinorelbine, paclitaxel, docetaxel and irinotecan.
Therapeutic Challenges
The major challenges in treatment of the above mentioned cancers are to improve early detection rates, to find new non-invasive markers that can be used to follow disease progression and identify relapse, and to find improved and less toxic therapies, especially for more advanced disease where 5 year survival is still poor. There is a great need to identify targets which are more specific to the cancer cells, e.g. ones which are expressed on the surface of the tumour cells so that they can be attacked by promising new approaches like immunotherapeutics and targeted toxins.